Finish tests

- Add sub-doc handling for SQLite fields
- Add casting for PostgreSQL BT on numeric value
- Add hasItems() to DocumentList
- Fix SQL syntax problems exposed by tests

tests/unit/Query/CountTest.php

@@ -2,7 +2,7 @@
 
 namespace Test\Unit\Query;
 
-use BitBadger\PDODocument\Field;
+use BitBadger\PDODocument\{Configuration, Field, Mode};
 use BitBadger\PDODocument\Query\Count;
 use PHPUnit\Framework\TestCase;
 
@@ -20,7 +20,12 @@ class CountTest extends TestCase
 
     public function testByFieldsSucceeds()
     {
-        $this->assertEquals("SELECT COUNT(*) FROM somewhere WHERE data->>'errors' > :errors",
-            Count::byFields('somewhere', [Field::GT('errors', 10, ':errors')]));
+        Configuration::$mode = Mode::SQLite;
+        try {
+            $this->assertEquals("SELECT COUNT(*) FROM somewhere WHERE data->>'errors' > :errors",
+                Count::byFields('somewhere', [Field::GT('errors', 10, ':errors')]));
+        } finally {
+            Configuration::$mode = null;
+        }
     }
 }